Xperia M doesn't work

[Ladyoftherings]

So, my sister downloaded this app called talkback and now her phone doesnt work. She tries to unlock it but she can´t and none of the buttons work. I want to reset it but I dont know how. Any help, please?

[Alexander1]

Hi and welcome to the community! Since you're new please be sure that you have checked out our Discussion guidelines.

If TalkBack is enabled you have to use two fingers to unlock the phone. You have to double tap on a icon (like settings) to access that app. To scroll in menus you also have to use two fingers. You'll find the TalkBack setting under settings > accessibility > TalkBack. 

If you want to reset the phone you can do this by repair the phone software using PC Companion: 

http://www.sonymobile.com/update

In PC Companion, press start on Support Zone > Start on Update the phone/tablet software > click on the blue highlight (Repair my phone/tablet). Do this without the phone connected. Follow the instructions on screen to perform the repair.